Heretofore, carburetors of the type described have generally been regarded as unsuitable for use in cold climates as they often show a tendency, when used in such climates, of the throttle valve to stick or become unable to slide, causing trouble in the control of the engine power output, since the air drawn into the carburetor is inevitably deprived of its heat by fuel evaporation therein to cause the moisture contained in the air to freeze to form ice on the throttle valve and thereabout.